'\" et
.TH TOLOWER "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
tolower,
tolower_l
\(em transliterate uppercase characters to lowercase
.SH SYNOPSIS
.LP
.nf
#include <ctype.h>
.P
int tolower(int \fIc\fP);
int tolower_l(int \fIc\fP, locale_t \fIlocale\fP);
.fi
.SH DESCRIPTION
For
\fItolower\fR():
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fItolower\fR()
and
\fItolower_l\fR()
functions have as a domain a type
.BR int ,
the value of which is representable as an
.BR "unsigned char"
or the value of EOF. If the argument has any other value, the behavior
is undefined. If the argument of
\fItolower\fR()
or
\fItolower_l\fR()
represents an uppercase letter, and there exists a corresponding
lowercase letter as defined by character type information in the current
locale
or in the locale represented by
.IR locale ,
respectively (category
.IR LC_CTYPE ),
the result shall be the corresponding lowercase letter. All other
arguments in the domain are returned unchanged.
.P
The behavior is undefined if the
.IR locale
argument to
\fItolower_l\fR()
is the special locale object LC_GLOBAL_LOCALE or is not a valid locale
object handle.
.SH "RETURN VALUE"
Upon successful completion, the
\fItolower\fR()
and
\fItolower_l\fR()
functions shall return the lowercase letter corresponding to the
argument passed; otherwise, they shall return the argument unchanged.
.SH ERRORS
No errors are defined.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIsetlocale\fR\^(\|)",
.IR "\fIuselocale\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 7" ", " "Locale",
.IR "\fB<ctype.h>\fP",
.IR "\fB<locale.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
